My idea for an SCP object would be an abandoned factory which starts to show anomalous properties where it starts to expel large amounts of an extremely toxic gas which can destroy any organic matter it comes in contact with. As well as that, there will be occurrences of living objects emerging out of the factory such as an organism made of a sticky tar like substance cloaked in the same thick smog which the factory produces. An occurrence of this creature escaping and destroying a massive amount of life which comes near it is a possibility. The factory could produce a few different organisms which are all in some way based on pollution.
There would be a fence around the factory to prevent unauthorised access to the site and many guards would be stationed around in case of another organism emerging out of the abandoned factory. After another large amount of gas is released, the Foundation would instead use robotic guards to patrol the site which are'nt affected from the pollution based lifeforms.
I got this idea from a friend who makes up ideas for giant (and I mean giant, many of these entities are over 1000 metres in height) monsters which all are based on something to do with our planet. I based one of the pollution organisms which emerges from the factory on a creation of my friend called "Black Smog" which he wanted in the story somewhere as it is one of his favourite creations. The organisms however would be scaled down so "Black Smog would be about 4 metres in size rather than 130 which it is in his original story.
